As is well known and understood, the arc of a normal lordotic curve in the lower spine is generally accepted to be of the order of 19 cm. As is also well known and understood, power weight lifters wear a leather belt tied around their waist while lifting, in an attempt to maintain this lordotic curvature in giving the optimum mechanical advantage to assist them in competition. Especially in "dead lifts" and in "squat lifts", the participant concentrates on positioning his, or her, legs and spine to give the greatest mechanical advantage during the lift itself. With such activities, the tendency of the lower spine is to straighten, and the use of the typical belt around the waist is tied sufficiently tightly in an attempt to maintain the lordotic curvature in providing the most mechanical advantage.
Experience has shown, however, that no matter how tightly the belt is kept--consistent with a degree of comfort--there still exists a tendency for the belt to "give", most noticeably when the lifter leans forward, and a degree of loss of the lordotic curve can thus result. Besides this resulting in a decrease in the bio-mechanical advantage available, such "give" has also been traced as a cause for the typical injuries of the lumbar postural muscles with result--namely, sprains and strains.